linux-kernel - Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA fails

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Message-ID: <564222CB.3000701@codeaurora.org>
Date:	Tue, 10 Nov 2015 11:00:59 -0600
From:	Timur Tabi <timur@...eaurora.org>
To:	Arnd Bergmann <arnd@...db.de>, Sinan Kaya <okaya@...eaurora.org>
Cc:	linux-arm-kernel@...ts.infradead.org,
	Abhijit Mahajan <abhijit.mahajan@...gotech.com>,
	Nagalakshmi Nandigama <nagalakshmi.nandigama@...gotech.com>,
	linux-scsi@...r.kernel.org, jcm@...hat.com,
	"James E.J. Bottomley" <JBottomley@...n.com>,
	linux-kernel@...r.kernel.org,
	Sreekanth Reddy <sreekanth.reddy@...gotech.com>,
	Praveen Krishnamoorthy <praveen.krishnamoorthy@...gotech.com>,
	cov@...eaurora.org, linux-arm-msm@...r.kernel.org,
	agross@...eaurora.org, MPT-FusionLinux.pdl@...gotech.com,
	Hannes Reinecke <hare@...e.de>
Subject: Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA
 fails

On 11/10/2015 10:47 AM, Arnd Bergmann wrote:
> What BenH was worried about here is that the driver sets different masks
> for streaming and coherent mappings, which is indeed a worry that
> could hit us on ARM as well, but I suppose we'll have to deal with
> that in platform code.
>
> Setting both masks to 32-bit is something that a lot of drivers do,
> and without IOMMU enabled, you'd hit the same bug on all of them.

Also note that I think that on PowerPC, the mask is set to 32 by default 
for all devices.  I don't think we do that on ARM64.  So on PowerPC, 
some drivers get away with not explicitly setting the mask.

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Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the
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